Treatment of tall oil



- Patented Mar. 17, 1942 TREATMENT OF TALL OIL Ernst Segessemann,Newark, N. J., assignor to -National Oil Products Company, Harrison,

N. J a corporation of New Jersey No Drawing. Application December 16,1939, Scrial'No. 309,704

(Cl. zoo-97.5)

8 Claims.

This invention relates to the production of valuable products from talloil and more particularly to the separation of tall oil into its mainconstituents, rosin and fatty acids.

Tall oil" or talloel which literally means "pine oil is the resinous andfatty by-product obtained chiefly in the production of paper pulp fromresin-bearing woods by the so-called sulphate process. In the sulphateprocess wood is digested with an alkaline liquor containing sodiumsulphate during which process tall oil accumulates in the form of itssodium soap on the surface of the waste liquor. The main constituents ofthis oil after acidification comprise fatty acids and resinic acids eachof which are valuable commodities in substantially pure form.

Various processes have been proposed in an attempt to effect separationof tall oil into its main constituents, i. e., fatty acids and resinicacids. One process comprises esterify'mg the fatty acids in tall oilwith a low boiling alcohol and separating the resulting fatty ester fromthe free rosin acids by distillation or by alkali extraction. Anotherknown process comprises esterifying the fatty acids with a polyhydricalcohol and distilling off the resinic acids. According to anotherprocess both the fatty acids and the resinic acids are esterified with apolyhydric alcohol and the resin esters are then catalytically split andthe liberated resinic acids distilled off. While the foregoing and otherknown processes have been employed with varying degrees of success,'theyall exhibit certain disadvantages, primarily in that only partialseparation is efiected. Moreover, the

fatty acid fraction obtained by these processes,

consisting mainly of a mixture of oleic, linoleic and linoleic acids, isnot particularly suitable for a wide variety of industrial uses. Usuallyhaving an iodine value of about 120 to 130, this fatty acid fraction (orits esters) shows some drying properties but these drying properties arenot pronounced enough for a drying oil of good quality. On the otherhand, this fatty acid fraction is too highly unsaturated to findextensive application in some of the largest fat-consuming industries,namely, the soap industry and in the manufacture of specialties for lthe textile and tanning trades, the bulk of fats used in theseindustries being of the more highly saturated type.

The general object of this invention is to provide an improved processof recovering from tall oil the fatty acids in substantially pure anduncontaminated form.

A further object of the invention is to provide an improved and moreeflicient process for separating the main constituents in tall oil,whereby the fatty acids recovered are in a substantially saturated form.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

These objects are accomplished according to the broader aspects of theinvention whereby tall oil is hydrogenated and then saponified with analkali metal hydroxide or with ammonia, and the resulting soap in thepresence of a solvent therefor is chilled, whereupon the soap of thefatty acids crystallizes out and is separated from the rosin soapremaining in solution by filtration or centrifuging. The fatty acids maythen be recovered from the soap, if desired, by splitting the latterwith an acid. Upon distilling off the solvent from the filtrate therosin soap may be recovered.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others thereof,which will be exemplified in the process hereinafter disclosed, and thescope of the invention will be indicated in the claims In carrying outthe process of the invention the tall oil is first subjected tohydrogenation under the influence of heat and pressure by passinghydrogen gas therethrough. The tall oil may be in a crude or a partiallyor completely refined state. as such, or it may first be dissolved in asuitable solvent, preferably a soap solvent, and the solvent solution ofthe tall oil hydrogenated. Durins the step of hydrogenation, anysuitable known catalyst may be used, such for example as nickel, whichfunctions very well. It is obvious of course, that other catalysts mayalso be used alone or in combination with a nickel catalyst. Thetemperature during hydrogenation may range from 100 C. to 250 C. ormore, the preferred range being about 145 C. to 185 C. The pressureduring the hydrogenating step may vary from atmospheric to the highestpressure possible under practical commercial conditions.

After the tall oil has been hydrogenated to the desired extent, it isdissolved in a soap solvent (if it was not hydrogenated in such asolvent solution). Any suitable soap solvent may be used, it beingpreferred to employ the lower aliphatic alcohols, such as, methyl,ethyl, propyl, isopropyl, butyl, isobutyl, etc., alcohols. The quantityof solvent used may be varied ,within wide limits depending upon thetype of solvent used and the degree to which the tall oil has been hy-Moreover, the tall oil mav be hydrogenated drogenated. Ordinarily theamount of solvent used should vary between 5 to parts per each part ofsoap by weight. The resulting hydrogenated tall oil solution is thensubjected to saponification by treatment with a uitable alkalinesaponifying agent, such as sodium hydroxide, sodium carbonate, potassiumhydroxide, ammonia, etc. In view of the fact that potassium and ammoniumhydroxides yield soaps which are more readily filtered after they areprecipitated out, their use is preferred. The alkaline saponifying agentshould be added in at least the stoichiometrical quantity and preferablyin excess thereof to insure complete saponification of both the fattyand rosin acids in the tall oil.

Upon completion of the saponification step, the resulting soap-solventmass is chilled or cooled to low temperatures whereby the: fatty acidsoaps, which are not as soluble as the rosin acid soaps, precipitateout. Preferably the soap solution is cooled down to and maintained at atemperature ranging'from 10 C. to -25 C. for a period of time sufilcientto permit precipitation of all the fatty acid soaps or at least themajor portion thereof. The precipitated soaps may then be removed fromthe resinate solution by filtration, centrifuging or by any othersuitable method. In order to free the fatty acid soaps from resinates,the former may be washed with a chilled solvent of substantially thesame temperature as the precipitated soap cake. The resulting fatty acidsoaps, particularly the stearates, are pure white solids containing noor only a minute quantity of resin or rosin soap. If the fatty acids aredesired, the soaps may, of course, be acidified in the usual manner. Itis obvious that the steps of hydrogenation and saponification may bereversed in order, 1. e., the tall oil may first be subjected tosaponification with subsequent hydrogenation before the chilling step.

For a fuller understanding of the nature and objects of the invention,reference should be had iodine value of 24.5) were dissolved in 800 ml.of methanol and sufiicient ammonia of 28% strength was added toneutralize all the fatty and resinic acids and leaving an excess of 10%of free ammonia in solution. The soap solution was then allowed to standat C. for 6 hours, which treatment caused the ammonia soap of the fattyacids to crystallize out of solution in a fine granular form. Theprecipitate was filtered off and washed with 400 ml. of methanolcontaining 3% of ammonia. The fatty acids, after splitting of theammonia soap, consist of a pure white solid having a rosin content of1.2%.

The ammonium resinate was then recovered from the filtrate by distillingoff the methanol.

Example III 100 gms. of distilled tall oil (having a rosin content of35%) was dissolved in 1200 ml. of ethyl alcohol. 18 gms. of drypotassium hydroxide were added and the mixture was refluxed until thepotassium hydroxide had completely dissolved. The soap solution was thenhydrogenated with 3 gms. of nickel catalyst at a pressure of 100atmospheres and at a temperature of 150 C. until no further hydrogen wasabsorbed. After removal of the catalyst by filtration, the soap solutionwas allowed to stand at 0 C. overnight. .The potassium soap of the fattyacids which had crystallized out in a fine granular form was thenfiltered off and washed with 400 ml. of fresh ethyl alcohol which hadpreviously been cooled to 0' C. The soap of the fatty acids was thendissolved in hot water and split with sulphuric acid to recover thefatty acids in their free state. The fatty acids thus obtained arepractically free from rosin consisting for the largest part of stearicacid.

to the following examples which are given merely to illustrate theinvention and are not to be construed in a limiting sense.

Example I Distilled tall oil (having a rosin content of 32%) washydrogenated at a pressure of 15 atmospheres and a temperature of 160C., using 2% of nickel powder as catalyst. After 2 hours the iodinevalue had decreased to 24.5. Analysis of the product showed that thefatty acids had been completely saturated and that one of the doublebonds of the rosin had been saturated. 100 gms. of the hydrogenatedproduct was dissolved in 1000 ml. of methanol and potassium hydroxide ofstrength was added in an amount sufficient to completely neutralize thefatty and resinic acids. The soap solution was then allowed to stand at5 C. for 6 hours to effect precipitation of the potassium soap of thefatty acids. The precipitated soap was then filtered off and washed with500 ml. of a 4% solution of potassium hydroxide in methanol to free itfrom residual rosin soap. The filter cake was then dissolved in waterand split with dilute sulphuric acid to recover the fatty acids in theirfree state. The fatty acids consist of a pure white solid having aresidual rosin content of .85%.

The rosin soap in the filtrate was then recovered by distilling off themethanol.

The potassium resinate (partially hydrogenated) was then recovered fromthe filtrate by distilling off the alcohol.

While the present invention is particularly adapted for the treatment oftall oil, it is within the purview of the invention to employ theprocess for separating resinic acids from fatty acids present in anymixture. While the process as hereinbefore described is highlypreferred, 1. e., using tall oil as the starting material, it is withinthe purview of the invention to use as the starting material the crudetall oil soap as recovered in the aforementioned sulfate-celluloseprocess which may or may not be refined before hydrogenation. By such aprocess the soap is hydrogenated and a solvent solution thereof chilledto precipitate out the fatty acid soaps. Such a process eliminates thesaponiflcation step, but due to the impurities in the crude soap whichact as a poison for the hydrogenation catalyst, it is preferred, asabove stated, to use as a starting material partially or completelyrefined tall oil.

Since certain changes may be made in carrying out the above processwithout departing from the scope of the invention, it is intended thatall matter contained in the above description shallv as new and desireto secure by Letters Patent is:

1. A process of treating tall oil to separate the fatty and. resinousconstituents thereof which comprises hydrogenating tall oil to convertthe unsaturated fatty acids therein to saturated fatty acids,saponifying the hydrogenated tall oil, decreasing the temperature of anorganic solvent solution of the resulting mass to effect precipitationof fatty acid soaps and removing the precipitated soaps from theremaining resinate solution. 7

2. A process of treating tall oil to separate the fatty and resinousconstituents thereof which comprises saponifying the fatty and rosinacids of tall oil, hydrogenating the resulting soap mass to convert theunsaturated fatty acid soaps therein to saturated fatty acid soaps,decreasing the temperature of the soaps in the presence of an organicsolventtherefor to effect precipitation of the fatty acid soaps andremoving the precipitated fatty acid soaps from the remaining resinatesolution.

3. A process of treating tall oil to separate the fatty and resinousconstituents thereof which comprises hydrogenating tall oil under theinfiuence of heat and pressure to convert substantially all of theunsaturated fatty acids into their saturated form, saponifying the acidsin the resulting mixture in the presence of an allphatic alcoholic soapsolvent with an alkaline agent, decreasing the temperature of the soapsolution to effect precipitation of the fatty acid soaps and removingthe precipitated fatty acid soaps from the remaining resinate solution.

4. The process of claim 3 wherein the alkaline agent used is potassiumhydroxide.

mass in methanol, saponifylng the fatty and rosin acids with potassiumhydroxide, decreasing the temperature of the resultant methanol soapsolution to effect precipitation of the fatty acid soaps and removingthe precipitated fatty acid soaps from the remaining methanol-resinatesolutions.

7. A process of treating tall oil to separate the fatty and resinousconstituents thereof which comprises dissolving distilled tall oil 'inethanol, saponifying the fatty and rosin acids with potassium hydroxide,hydrogenating the soap-ethanol solution to convert the unsaturated fattyacid soaps therein to saturated fatty acid soaps, decreasing thetemperature of the solution to effect precipitation of the fatty acidsoaps and removing the precipitated fatty acid soaps from the remainingresinate-ethanol solution.

8. In a process of treating saponified tall oil of the type in which theunsaturated fatty portion has been saturated by hydrogenation, the stepwhich comprises chilling a solution of such saponifled hydrogenated talloil in an organic solvent therefor to effect; precipitation of fattyacid soaps.

ERNEST SEGESSEMANN.

